32 



VASCULAR CRYPTOGAMS 



the lower and larger portion of the protoplasmic cell-contents contract- 

 ing into an oosphere. If the archegone remains unfertilised the prothal- 

 lium continues to grow into a comparatively large chlorophyllous structure 

 with rhizoids. 



The male prothalliuni and antherids are reduced to a still more 



Fig. 14. — 31arsilea salvatrix L. Longi- 

 tudinal section through megaspore, pro- 

 thallium, and embryo. «;«, starch 

 grains ; z, inner ccat ; ex, epispore ; c, 

 space beneath diaphragm ; pt, prothal- 

 lium ; zc7z, its rhizoids ; «, archegone ; 

 /, foot ; TV, root of embryo ; b, coty- 

 ledon ; si, mucilaginous envelope of 

 megaspore. (After Goebel, x 60.) 



^c^ « 



0)^ 



:^%:-. 



Fig. 15. — Marsilea salvatrix. A, prothallium 

 j>t, projecting from ruptured coat r of mega- 

 spore ; si, layers of mucilage forming funnel, 

 with antherozoids. B, vertical section of 

 prothallium pt ; 0, oosphere ; a, stigmatic 

 cells. (After Goebel, greatly magnified.) 



rudimentary condition than in the Salviniacese. The contents of the 

 microspore divide into three cells, one of which (the prothallium) 

 remains sterile, the other two constituting the antherid. The contents 

 of each of these two cells again divide into sixteen antherozoid-mother- 

 cells. From the nucleus of each of these is formed an antherozoid ; 



